1. Field of the Invention
The present invention relates to novel fluorine-containing copolymers and their use for coating and impregnating various substrates such as textile, leather, wood, non-woven fabrics metals, concrete, and, more particularly, paper and similar articles for imparting oil- and water-repelling properties thereto.
2. Description of Prior Art
Numerous fluorinated derivatives are already being proposed for obtaining these properties. However, even though such derivatives exhibit good properties on textiles and on leather, in order to obtain the same properties on paper and similar articles, it is necessary to employ them with an active ingredient content that is far too high (in fact, an amount of carbon-linked fluorine that is too high) in order to obtain an economically acceptable result.
By way of products that are more specially suitable for paper, chromium complexes have been proposed in French patents 1 172 664 and 2 022 351 and in U.S. Pat. No. 3,907,576 Such complexes which do in fact impart useful oil-repellent properties to paper and similar articles nevertheless suffer from the disadvantage of having a green color and of transferring this color to substrates to which they are employed, thus limiting their use.
Polyfluoroalkyl or cycloalkyl phosphates have also been proposed for papermaking use (French patents 1 305 612, 1 317 427, 1 388 621, 2 055 551, 2 057 793 and 2 374 327, U.S. Pat. Nos. 3,083,224 and 3,817,958, German patent 2 405 042) as well as hydroxypropyl polyfluoroalkyl phosphates (U.S. Pat. No. 3,919,361). However, these products which confer good oil-resisting properties to paper suffer from the serious handicap of not conferring any water-repelling properties thereto. Because of this, paper treated with these products does not exhibit any protection vis-a-vis aqueous product. Moreover, these products have no sizing ability and even strongly reduce the effectiveness of sizing agents, thus causing problems with writing and printing.
Moreover, the evolution of culinary techniques resulting from increasing use of microwave ovens has required new materials to be developed for food packaging. The use of aluminum receptacles is not allowed, plastics materials withstand heat poorly and moreover require large amounts of petroleum-based products to be used, and the problem of destroying and recycling them are considerable. The material of choice would hence be cardboard if it were possible to impart excellent water- and oil-repellent properties thereto.
For the treatment of paper and similar articles, the use has been proposed of perfluoroaliphatic acrylic and methacrylic copolymers with dialkylaminoalkyl cationic acrylic or methacrylic esters in their salt, quaternized or N-oxide form. However, the compositions claimed suffer from the disadvantage of possessing insufficient water and/or oil-repelling properties (U.S. Pat. No. 4,147,851; EP 0109.171) or involve the presence of a co-monomer which apparently is suspected of giving rise to long term toxic effects (French Patent 2 476 097).